The present invention relates generally to a modified polyamide polymer having markedly improved wetfastness properties. In particular, the present invention relates to a modified polyamide 6 polymer for textile fiber that significantly reduces dye bleed performance in water and improves colorfastness to laundering.
Polyamide (nylon) polymers such as, for example, polyamide 6 and polyamide 6,6 are commonly used in the production of fibers and yarns for elastic fabrics, especially swimwear. When textile fibers and yarns made of polyamide are used for elastic fabric applications, they exhibit a wetfastness problem.
It is known that stabilizers can be used to improve certain properties (i.e., light and heat stability) of some polyamide polymers. One such class of stabilizers is the hindered amine light stabilizer class, which includes compounds derived from polyalkylpiperidine. For example, polyamide 6 forming monomers may be polymerized in the presence of water, carboxylic acids, and hindered piperidine derivatives (polyalkylpiperidines) to form a modified polyamide polymer that is stabilized against heat and light degradation. Although the stabilizers do much to stabilize the polymer against heat and light, such additives themselves do little to stabilize the wetfastness of the polymer.
A need, therefore, exists for a wetfast polyamide polymer with resistance to dye bleeding in water, as well as colorfastness to laundering.
It is an object of the present invention to improve the wetfastness properties, particularly dye bleed performance and colorfastness to laundering, of polyamide 6.
It has now been found that this object may be achieved by polymerizing polyamide-forming monomers in the presence of a hindered piperidine derivative and a carboxylic acid as a chain regulator to obtain a modified polyamide polymer containing a high number of amino end groups. Most preferably, the hindered piperidine derivative and carboxylic acid are present in amounts sufficient to form a modified polyamide polymer having at least about 30 percent or greater of the amino end groups being secondary or tertiary amines.
The above and other objects, effects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments thereof.